TOM

%typeterm Term {
  implement { Term }
  is_sort(t) { t instanceof Term }
}

%op Term a() {
  is_fsym(t) { t instanceof A }
  make() { new A() }
}

%op Term f(x:Term) {
  is_fsym(t) { t instanceof F }
  get_slot(x,t) { ((F)t).getX() }
  make(t) { new F(t) }
}

public class SimpleMatch {
  %match(subject) {
    f(a()) -> { return "Matched f(a())"; }
    f(x) -> { return "Matched f(" + `x + ")"; }
    x -> { return "Matched " + `x; }
  }
  return "No match";
}